Sheet conveying mechanism



March 22, 1966 A. ERK 3,241,665

SHEET CONVEYING MECHANISM Filed Jan. '7, 1963 2 Shee ts-Sneet 1 Fig.1

SHEET CONVEYING MECHANISM Filed Jan. 7. 1965 2 Sheets-Sheet 2 gel 45 United States Patent f 2 Claims. n. 209 14) The invention relates to a conveyor mechanism for cut sheets or packs of such sheets of paper or similar materials which mechanism is capable of braking the sheets, which come from a high speed machine, to a speed suitable for some cooperating mechanism.

Various braking devices are known for slowing down single sheets or superposed sheets on their way between cutter and stacker.

It is a primary object of the present invention to provide a device capable of retarding sheets coming from a high speed machine to a lower speed suitable for a cooperating mechanism, which device, however, is also capable, at low operating speeds, for instance at a gradual start or at the stopping of said machine, of reducing the braking action to zero or even to accelerate the transfer of the sheets to said cooperating mechanism.

The braking devices known heretofore could not satisfy said conditions.

The device of the invention comprises an externally driven pair of rollers on shafts which are movable towards each other from a first position into a second operative position. In said first position, there remains between the rollers a gap sufiicient for free passage of the sheets; in said second operative position, the rollers contact the sheets or superposed sheets with pressure so as to impart to the sheets a transfer motion corresponding to the surface speed of the pair of rollers. In addition, the device comprises means for displacing the rollers from the one position into the other position where the rollers grip the delivered sheets or packs as a function of the timed spacing of said sheets. Finally, the roller pair is provided with a drive which drives the rollers at a speed of rotation which is independent of the speed at which the sheets are fed.

As will be understood from the foregoing description, the device is provided with separate drive means, one of which controls rhythmically the spacing of the rollers, operates at the rhythm of the time intervals between the delivered sheets and is preferably directly coupled with the high speed machine delivering the sheets to be conveyed; the second driving means provides for a rotational speed of the transfer rollers completely independent of the speed of the delivered sheets and also of the speed of the high speed machine. Said rotational speed is adjusted to a speed suitable for the cooperating mechanism, for instance to a speed suitable for stacking the sheets. For this purpose, it is of advantage to drive the rollers continuously at uniform speed. As a result, the conveyor device of the invention brakes the advance of the sheets at high speeds of the machine, but may accelerate the movement at low speeds, whereby in both cases a speed suitable for the further treatment is obtained after the sheets have passed the roller pair.

It is of advantage to move the rollers in operative position in such a way that they grip the sheets only for a certain time at their trailing end.

In this way, buckling of the sheets during the slowdown is prevented, particularly when the sheets consist of thin paper or the like.

Further advantages and details of the invention will i be readily understood by reference to the following description of an embodiment of the invention which is diagrammatically illustrated in the accompanying drawing.

3,241,665 Patented Mar. 22, 1966 In the drawing,

FIG. 1 is a fragmentary view in side elevation of the essential parts of a transfer device embodying features of the present invention, and

FIG. 2 is a diagrammatic view of a plant where the conveyor mechanism of FIG. 1 transfers the sheets coming from a cutter to the stacking device at a speed suitable for this purpose.

Referring first to FIG. 1, the transport rollers 1 and 2, cooperating as roller pair, are shown in their operative position, the pack of sheets therebetween being designated with the reference numeral 3. Mounted on shaft 4 of roller 1 and on shaft 5 of roller 2, outside the path of the sheet packs, are gears which are in engagement through intermediate gears 6 and 6' mounted on shafts 7 and 8, respectively. For timed adjustment of the spacing between shafts 4 and 5, shaft 4 is supported at its ends in two rigidly connected bell cranks which consist of the two lever arms 9 and 10 and are fulcrumed at 11. The location of said fulcrum 11 is selected so as to maintain proper engagement of the drive gears on shafts 4 and 7 when the lever arm 9 is swung out from the shown operative position into the somewhat higher end position where the two rollers 1 and 2 do not grip the passing sheets.

One of the shafts 5, 7, or 8 is connected to a separate continuously running motor to ensure continuous drive of the two rollers 1 and 2. It is of advantage to use a motor whose number of revolutions per minute is adjustable within certain limits or a constant speed motor which is connected to the driven shaft by means of an infinitely variable speed drive transmission. In both cases, the rotational speed of the rollers 1 and 2 can be adjusted, during operation, to the desired value which will depend on the properties of the treated sheet material.

The second drive required to operate the device of the invention actuates, in the illustrated embodiment, the lever arm 10. Said drive comprises a cam disc 12, the shaft of which is connected with the shaft of the coordinated collecting cylinder in such a Way that it makes also a full revolution for every revolution of the collecting cylinder. The periphery of the cam 12 contacts a sensing roller 14 which pivots on a lever 15 about a fixed fulcrum 16 and transfers its movement to the lever arm 10 over an adjustable screw 17. The cam 12 is so formed as to keep for the major part of one revolution the roller I lifted from the roller 2, and it is flattened only for a smaller portion of its periphery by a reduction of its diameter. When said flattened part passes below the sensing roll 14, the roller 1 takes up the operative position shown in the drawing, whereby the required contacting pressure against roller 2 is obtained by the weight of roller 1 and lever arm 9. In order to ensure said pressure, I provide, in the position shown, an air gap between screw 17 and lever 15. By adjusting the screw 17, the width of said air gap is adapted to the thickness of the transferred packs of sheets; said thickness may vary, though hardly during delivery of a web fed into the cutter but on change of the reel, as a function of the paper used.

As already stated, the cam 12 runs synchronously with the shaft of the collecting cylinder. For the mechanical connection of the shaft of the collecting cylinder with shaft 13, it is of advantage to use a differential gear (register gear) which is used to change the angle between driving and driven shaft of said gear during operation, whereby the synchronism of the two shafts is maintained prior to, and after, such change. Such a gear allows to adjust the angle between cam and collecting cylinder also during operation. This means that closure of the gap between rollers 1 and 2 may be timed in relationship to the passing packs and that the length of the portion of the pack acted upon by the rollers can be adjusted.

As the cam disc 12 revolves synchronously with the collecting cylinder, the time of one revolution corresponds to the time interval between the feed of two subsequent sheets to the collecting cylinder, and, therefore, also to the intervals in which a pack delivered from the collecting cylinder could reach the bite between the rollers 1 and 2. In said rhythm, said gap is alternately opened and closed; hereby, however, a pack is not gripped at every closure since only after a sufiicient number of cycles a new pack enters the bite between the rollers 1 and 2. Therefore, even on strong retardation of a pack, there is no risk that the leading edge of a subsequent pack contacts the trailing edge of the preceding pack so as to produce buckling of said subsequent pack. After the trailing edge of a pack has left the bite of the rollers, it is also easily possible to leave the rollers for a short time in the closed position without the risk that the leading edge of a subsequent pack could be arrested. Neither is it necessary to exchange the cam 12 when the cutter is adjusted for another length of the sheets; it is sufficient to adjust accordingly the register gear for driving the shaft 13.

As an alternative to the described operation, shaft 4 may be swung about shaft 1 to bring the transport cylinders 1 and 2 in operative position, or it may be raised from the shaft 5 in a straight line in timed relationship with the spacing of the sheets. The opening of the roller pair need not be controlled from the shaft of the collecting cylinder by mechanical means; electromagnetic means may be used which may be actuated in the required rhythm by a switch disk synchronously driven with, or directly mounted on, the shaft of the collecting cylinder. For this purpose, the register gear may be replaced by adjustable electric delay means.

The described device is particularly suitable for machines where cut sheets are assembled on collecting cylinders to packs of uniform numbers of sheets, which packs are then stacked after having passed the conveyor device. FIG. 2 shows diagrammatically such a machine where the web supplied from a reel is checked for defects and cut into sheets, whereupon the good sheets and the reject sheets are passed to separate stacking means. In the upper part of FIG. 2, the various operating stations are shown, which are passed by the web or the cut sheets, while the lower part illustrates schematically the mechanical drives for said stations. First, I will describe briefly the sequence of the stations.

Drive rollers 19 support the supply roll 18 from which the web 20 passes over a tension roll 21 and a guide roll 22 through the devices 23 and 24 at the upper and lower face of which the web is subjected to a sequential photoelectric surface scanning examination. The correct speed of the web is ensured by a pair of drawing rolls 25 which guide the web to a rotating transverse cutter 26 which severs sheets of uniform length. Such sheets are then passed by conveyor belts 28 to a switch 29 which is controlled by the electric pulses generated in the devices 23 and 24. The speed of the conveyor belts 28 is higher by a certain ratio than the speed of the web 20 so as to leave between the sheets the distance required for their further treatment. The switch controls two separate paths 30 and 31, whereby path 30 receives the sheets found acceptable in the sorting operation, and path 31 receives the rejects. Either path 30 and 31 leads first to a collecting cylinder 32 or 33, respectively. Said collecting cylinders complete always one revolution in the time interval between two cutting actions of the cutter 26. Thereby, the circumferential speed of said cylinders corresponds to the speed of the conveyor belts 28 so that a sheet fed to the collecting cylinder is placed with its leading edge exactly on the leading edge of a sheet which already rotates with the cylinder. In this way, packs of sheets are formed on the collecting cylinders. As soon as the number of sheets in said packs has reached a predetermined limit, the packs are taken off the cylinders by switches 34 and 35, respectively, which are displaceable between two end positions and pass the packs onto the conveyor belts 36 and 37, respectively. For actuating said switches, it is necessary to count the delivered sheets, which may be done, for instance, by means of photoelectric counters in the paths 30 and 31. When leaving the collecting cylinders, the packs have still a speed which equals the circumferential speed of the collecting cylinders 32, 33. The packs are then passed by conveyors 36, 37 over tables 38, 39 to a conveyor device as shown in FIG. I. Said device is shown in FIG. 2 essentially only by the rolls 1 and 2, while the members 9 to 17 which adjust the spacing of the shafts of said rolls, are only schematically indicated by the lever arms 9 and 10, the sensing roll 14, and the cam disc 12. By means of said conveyor devices, the acceptable packs pass from the table 38 to the stacker 40, and the reject packs from the table 39 to the stacker 41, at a speed most suitable for the stacking operation.

The drive trains in FIG. 2 comprise a main drive motor 43 driving over a drive train 53 directly the roller pair 25, whose speed of rotation determines the operating speed of the entire plant. A further drive branches ofii the drive train 53, which drive leads over the drive train 54 and infinitely variable speed drive transmission 55 to the drive rollers 19 of the supply roll 18. The variable speed drive transmission 55 is provided because slippage may take place according to the smoothness of the web surface; preferably, I provide an automatic control for the drive transmission which is responsive to an upper or lower end position of roll 21.

A further drive train 56 branches off drive train 53 and leads over an infinitely variable speed drive transmission 57 and drive train 58 to the cutter 26. The transmission 57 is adjusted in accordance with the desired length of the cut sheets. Still another drive train branches off drive train 58 and is preferably constituted by a vertical shaft 59 from which drive trains 60 to 64 branch off. Branch 60 actuates the switch 29 and part of the transport means for the cut sheets. Branches 61 and 63 are provided to drive the collecting cylinders 33 and 32, respectively, whereby these drive trains also operate the conveyor belts, which advance the individual sheets at a rate corresponding to the circumferential speed of the collecting cylinders.

The two branches 62 and 64 drive the cam discs 12 which effect the displacement of the shafts of the rolls 1 and 2 into their respective end positions.

Separate motors 44, 45 drive the pairs of rolls 1, 2; the rotational speed of said motors is adjustable, or they are connected to an adjustable gear, so that the rolls 1, 2 are driven at a speed of rotation which is independent of all the other drives.

Additional drive trains 65 and 67 branch off trains 61 and 63, respectively (see FIG. 2), which drive the bands pressing the sheets against the surfaces of the collecting cylinders 32 and 33.

Infinitely variable speed drive units 66 and 68 are provided in the trains 65 and 67, respectively, which compensate for slippage obtaining between the bands and the collecting cylinders, which causes displacement of the individual sheets of a pack, so that the leading edges of the individual sheets register and do not lie in scaled formation.

In the application of my retarding or conveying device shown in FIG. 2, the device is used in combination with the photoelectric surface scanning means 23, 24 in front of the cutter means and the switch 29 behind the cutter means, in the direction of travel of the web and sheets; this arrangement results in a particular manner of operation of the two pairs of cylinders 1, 2 insofar as the time intervals between the stacking of the produced packs are entirely irregular. Said intervals depend, for each of the two cylinder pairs, on the number of sorted out rejects. The construction of my device solves the problem to maintain in each case the most favorable stacking speed of packs in spite of an irregular timing of the feed of such packs, independently of the operative speed of the sorting and cutting means.

I claim:

1. In a sheet handling machine, in combination with sorting and reject means, at least one collecting cylinder collecting sheets received from said sorting and reject means in superposed position to packs, stacking means for said packs, and between said collecting cylinder and said stacking means a conveyor mechanism comprising a pair of coacting transport rolls, the shaft of one of said rolls being displaceable with respect to the shaft of the other of said rolls so as to raise said roll from an operative position, in which the two rolls grip sheets fed into their bite, into an inoperative position, lever means actuating said displaceable shaft so as to raise said roll, cam means actuating said lever means in timed relation with the delivery of sheets from said collecting cylinder into the bite of said transport rolls, and a cam shaft driving said cam means, said cam shaft being operatively connected to said collecting cylinder so as to rotate with the same speed as said cylinder.

2. A conveyor mechanism as claimed in claim 1 comprising means adjusting the timing of said cam means.

References Cited by the Examiner UNITED STATES PATENTS 2,298,368 10/1942 Goebel. 2,804,974 9/1957 Noon 20974 2,873,968 2/1959 Grobman 271-51 2,950,640 8/1960 Camp 20971.2

ROBERT B. REEVES, Primary Examiner. 

1. IN A SHEET HANDLING MACHINE, IN COMBINATION WITH SORTING AND REJECT MEANS, AT LEAST ONE COLLECTING CYLINDER COLLECTING SHEETS RECEIVED FROM SAID SORTING AND REJECT MEANS IN SUPERPOSED POSITION TO PACKS, STACKING MEANS FOR SAID PACKS, AND BETWEEN SAID COLLECTING CYLINDER AND SAID STACKING MEANS A CONVEYOR MECHANISM COMPRISING A PAIR OF COACTING TRANSPORT ROLLS, THE SHAFT OF ONE OF SAID ROLLS BEING DISPLACEABLE WITH RESPECT TO THE SHAFT OF THE OTHER OF SAID ROLLS SO AS TO RAISE SAID ROLL FROM AN OPERATIVE POSITION, IN WHICH THE TWO ROLLS GRIP SHEETS FED INTO THEIR BITE, INTO AN INOPERATIVE POSITION, LEVER MEANS ACTUATING SAID DISPLACEABLE SHAFT SO AS TO RAISE SAID ROLL, CAM MEANS ACTUATING SAID LEVER MEANS IN TIMED RELATION WITH THE DELIVERY OF SHEETS FROM SAID COLLECTING CYLINDER INTO THE BITE OF SAID TRANSPORT ROLLS, AND A CAM SHAFT DRIVING SAID CAM MEANS, SAID CAM SHAFT BEING OPERATIVELY CONNECTED TO SAID COLLECTING CYLINDER SO AS TO ROTATE WITH THE SAME SPEED AS SAID CYLINDER. 